Method and apparatus for tube forming

ABSTRACT

A tube forming method and apparatus for forming a pair of radially extending axially spaced ribs on a tube in a single operation. The apparatus includes a main clamping block having upper and lower block elements and a two-piece floating clamping block disposed for movement axially toward and away from the main clamping block. An axially moveable punch means is provided for selective movement into and out of the tube while the tube is held within the main clamping block and in the floating block and for guiding the tube while concurrently forcing the floating block axially toward the main block to cause the formation of axially spaced radially extending ribs on the tube at points in the tube on axially opposite sides of the tube portion clamped within the floating block.

United States Patent [191 Bagby 1 Feb. 18, 1975 METHOD AND APPARATUS FOR TUBE FORMING [75] Inventor: Thomas L. Bagby, Washington, 111.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Aug. 24, 1973 [21] Appl. No.: 391,338

[52] U.S. Cl 72/370, 72/59, 72/398, 72/403 [51] Int. Cl. B21d 15/06 [58] Field of Search 72/58, 62, 370, 394, 395, 72/396, 397, 398, 403, 59, 402

[56] References Cited UNITED STATES PATENTS 616,764 12/1898 Bourke 72/59 2,465,677 3/1949 Deverall 72/58 2,490,695 12/1949 Leutheuser 72/58 2,773,538 12/1956 DeMers 1 72/59 2,825,387 3/1958 Alltop et a1 72/59 2,954,064 9/1960 DeMers 72/59 3,083,754 4/1963 72/59 3,566,664 3/1971 72/402 3,595,047 7/1971 Fanning et a1. 72/58 FOREIGN PATENTS OR APPLICATIONS 1,059,269 8/1957 Germany 72/399 692,555 8/1964 Canada 72/59 Primary ExaminerC. W. Lanham Assistant ExaminerE. M. Combs Attorney, Agem, or FirmPhillips, Moore, Weissenberger Lempio & Strahala [57] ABSTRACT A tube forming method and apparatus for forming a pair of radially extending axially spaced ribs on a tube in a single operation. The apparatus includes a main clamping block having upper and lower block elements and a two-piece floating clamping block disposed for movement axially toward and away from the main clamping block. An axially moveable punch means is provided for selective movement into and out of the tube while the tube is held within the main clamping block and in the floating block and for guiding the tube while concurrently forcing the floating block axially toward the main block to cause the formation of axially spaced radially extending ribs on the tube at points in the tube on axially opposite sides of the tube portion clamped within the floating block.

10 Claims, 4 Drawing Figures PATENTED FEB 1 81975 sum 10F 2 METHOD AND APPARATUS FOR TUBE FORMING BACKGROUND OF THE INVENTION A need exists for forming radially extending ribs in thin-walled steel tubing. More particularly, it is desir able to provide a pair of radially extending axially spaced ribs in an end portion of a thin-walled steel tube in a single operation. Tubes equipped with such ribs are frequently utilized as communication conduits for vari ous fluids between the various components of a vehicle or like user. The spacing groove formed between the spaced apart ribs is utilized for mounting O-ring type seals or the like for sealing purposes when the end of the tube is mounted within a suitable fixture.

Prior art rib forming apparatus used to create such O-ring grooves in steel tubing often required at least four separate forming operations in order to form the desired ribs. Such multiplicity of steps was obviously expensive and time consuming.

Also, a serious problem manifest by such prior art apparatus was the production of excessive frictional heat and rapid component wear occasioned by the necessary sliding contact between the apparatus and the tube being formed.

Furthermore, such prior art arrangements often utilized a die forming method for forming the ribs which, unlike a simple folding method, tended to work harden the tubing metal and render the tube susceptible to fracture.

Some prior art attempts to solve some of the above problems by utilizing a deformable forming element in a single operation are shown with various arrangements in U.S. Pat. Nos. 2,417,202 and 3,595,047 to Hull et al. and Fanning et al. respectively.

SUMMARY AND OBJECTS OF THE INVENTION The instant invention provides an economical and efficiently operable rib forming apparatus for steel tubing. A hydraulically actuated main clamping block is provided with a tube receiving axial bore therein. A floating two-piece clamping block is slideably mounted upon said main clamping block and is axially moveable relative thereto. The tube to be formed is placed and clamped within the bores formed within the main clamping block and the floating clamping block. The bore within the floating clamping block is provided with axially spaced counterbore means adopted to receive tubing material during the forming operation. A selectively moveable punch means having an elongated reduced section and an enlarged shoulder portion is moved axially into the end portion of the tube until the shoulder portion engages a portion of the floating clamping block and moves said floating clamping block axially toward the main clamping block to confine a portion of said tube between the floating block and the main clamping block and to fold said tube portion and cause material therein to fill said axially spaced counterbore means to form the desired spaced ribs.

The main object of the present invention is to provide a tube forming apparatus which forms two spacedapart ribs on the end portion of a tube in a single stroke folding operation.

Another object of the invention is to provide a tube forming apparatus having a main clamping block and a floating clamping block moveable relative to the main clamping block to an extent limited by adjustable stop means.

A further object ofthe present invention is to provide a tube forming apparatus having relatively moveable clamping blocks which are spring biased apart for rapid repositioning of components subsequent to the accomplishment of a forming operation.

Other objects and advantages of the invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of the present tube forming apparatus showing the component parts thereof in operative disposition;

FIG. 2 is an enlarged end-view of a portion of the up paratus shown in FIG. I and taken along the line IIIl of FIG. 1;

FIG. 3 is a sectional view of the apparatus taken along the line III-III of FIG. 2 and showing the punch means operatively disposed within the tube to be formed; and

FIG. 4 is a sectional view, similar to FIG. 3, showing the disposition of the parts after a forming operation.

DETAILED DESCRIPTION With reference to FIG. 1 in the drawings, the present tube forming apparatus is indicated generally at 10. It includes a main clamping block 12 and a reduced dimension floating block 14 adjacently disposed and an elongated punch means 16 axially spaced from the floating block 14.

The main clamping block 12 includes a longitudinally disposed bore 17 formed therethrough and is equipped with a separable fixed lower half 20 and a moveable upper half 22 divided along a horizontal parting plane 18 which also bisects the bore 17. The upper half 22 is adapted for limited movement in a direction normal to the parting plane 18 by means of a hydraulic jack, shown partially at 24. A plurality of guide pins 26 are utilized for aligning the upper and lower block halves during such movement. As best shown in FIG. 2, each pin 26 has one end press-fitted into a vertical receiving bore 28 formed in the upper half 22 and has the other end slideably mounted within a bearing sleeve 30 retained in an aligned bore 32 formed into the lower half 20.

As shown most clearly in FIG. 3, the main clamping block 12 has an annular protuberance 34 thereon which extends longitudinally to a point proximate the floating block 14. The protuberance 34 is disposed concentrically about the bore 17 and is provided with a distal face 36.

The floating block 14 is provided with a similar bore 38 formed therethrough which bore is coaxial with the bore 17. The floating block is also separable along the parting plane 18 into a lower portion 40 and an upper portion 42.

As may be appreciated by reference to FIG. 2, the upper and lower portions of the floating block are slideably secured to the corresponding upper and lower halves of the main clamping block I2 by means of a plurality of large pins 44 which are disposed in parallel alignment with the bores 17 and 38. As best shown in FIG. 3, each pin 44 has one end thereof firmly pressfitted into a bore 46 formed in one of the main clamping block halves and its other end slideably mounted within a bearing sleeve 48 secured within an aligned bore 50 in the corresponding portion of the floating block 14.

Axial movement of the floating block 14 relative to the main block 12 is adjustably limited by a pair of stop bolts 52 which individually extend through a clearance bore 54 formed through the respective upper and lower floating block portions 42 and 40 and are screwthreadably engaged within a corresponding pair of threaded apertures 56 formed in the corresponding upper and lower main block halves 22 and 20. A nut 58 is mounted upon each of the stop bolts for locking them in a predetermined disposition relative to the main clamping block 12. The floating block portions 40 and 42 are individually urged axially outwardly against the heads of the bolts 52 by means of a pair of helical springs 60, or like means, which are individually disposed between the corresponding pairs of upper and lower portions of the floating and main blocks 12 and 14.

The floating block 14 is also provided with an annular recess 62 which is disposed to receive the protuberance 34 of the main block 12 and which includes a bottoming surface 64 axially spaced apart from the distal face 36 of the protuberance. Axial movement of the floating block 14 toward the main block is limited by the abutting engagement of the bottoming surface 64 against the distal face 36.

A pair of counterbores 66 and 68 are disposed at axially opposite end portions of the bore 38 in the floating block 14. These counterbores are adapted to receive folded tubing material during the rib forming operation as will be more fully explained hereinafter.

The punch means 16 includes a shoulder 70 which extends from a reduced diameter portion 72 which is operatively disposed within the bores 17 and 38. The reduced diameter portion 72 has a slightly tapered end portion 74 for facilitating insertion thereofinto the tubing to be formed. The punch is adapted for limited reciprocative movement within the bores by means of a suitable actuating device, not shown.

OPERATION In operation, the hydraulic jack 24 is retracted to separate the upper and lower halves of the main block 12 along the parting plane 18. The upper and lower portions of the floating block 14 are concurrently separated therewith due to their attachment to the corresponding halves of the main block by means ofthe mounting pins 44.

With the punch means 16 disposed without the bores 17 and 38, as shown in FIG. 1, a piece of tubing 80 to be formed is inserted within the bores 17 and 38 so that an end portion 81 thereof extends a predetermined distance beyond the outward confines of the floating block 14. Such predetermined distance, as will be more fully explained hereinafter, is substantially equal to the distance between the distal face 36 of the protuberance and the bottoming surface 64 of the recess 62.

With the tube in place, actuation of the hydraulic jack 24 causes closure of the respective halves of the main block 12 and of the floating block 14. The bore 17 of the main block is sized such that the tube 80 is clamped in a fixed position thereby during the forming operation. While not shown, threads or rifling may be formed on the bore 17 for increased clamping effectiveness, if required. The bore 38 of the floating block is similarlysized so that, for its limited length, the tube is lightly gripped thereby.

Once the tube is clamped within both the main and floating blocks, inward movement of the punch means 16 causes a telescopic insertion of the reduced diameter portion 72 into the interior of the tube and the subsequent abutment of the shoulder against the end 81 thereof.

As can be readily seen with reference to FIG. 3, the only portions of the tube which are not fully constrained between the punch means shoulder and the blocks is the length of tube which extends between the face 36 and the inner portions of bore 38 and the length of tube which extends between the outer end of the bore 38 and the shoulder 70. Consequently, upon the inward stroke of the punch means, these lengths of tube are folded outwardly and received by the pair of counter-bores 66, 68 to form radially extending ribs 82 and 84 as shown in FIG. 4. It should be noted that as the rib 82 is being formed, the bearings 48 permits the floating block 14 to move inwardly toward the main block 12 slideably along the pins 44 to accommodate the resultant shortening of the tube.

The inward stroke of the punch means is completed when the shoulder 70 engages the floating block 14 and the floating block engages the main block 12.

An annular groove 86 is formed between the ribs 82 and 84 because the lengths of tube being gripped by bores 17 and 38 are held to their original diameter. Upon retraction of the punch means 16 from the tube and the reopening of the blocks 12 and 14, the formed tube can be readily removed and another tube can be inserted for a similar forming operation.

It should also be noted that the ends of bores 17 and 38 in the forming area are provided with smoothly curved edges to prevent damage to the tube during forming and to preclude the formation of undue stress risers.

Within appropriate limits, the contour of the groove and ribs formed by the present apparatus may be varied by means of slight variation in the forming areas of the blocks. For instance, the radial height of the ribs 82 and 84 may be varied by controlling the distance between the faces 36 and 64 through the proper adjustment of the travel of the stop bolts 52 and by providing a corresponding length of tubing extending from the floating block 14. Also, the width of the groove 86 could be varied by means of appropriate axial lengthening or shortening of the bore 38. The width of each of the ribs 82 and 84 could be modified by adjusting the effective axial depth of counter-bores 66 and 68, respectively. Also, variations in tube wall thickness could be accommodated by means of providing the reduced diameter portion 72 with the appropriately different outer diameter.

While the invention has been described with particu lar reference to the preferred embodiments, it is apparent that variations and modifications are possible within the purview of the inventive concepts. No limitation with respect to such variations and modifications is intended, except by the scope of the appended claims.

I claim:

1. Apparatus for forming a tube comprising; main block means for holding a first portion of said tube to be formed, floating block means for holding a second portion of said tube to be formed, said floating block means being movable relative to said main block means in a direction coincident with the axis with said tube, said floating block means including spaced-apart first and second counterbore means for receiving third and fourth portions of said tube and forming said third and fourth portions into radially extending ribs on said tube by folding said third and fourth portions upon axial movement of said floating block means toward said main block means, punch means for non-forceable passage into the interior of said first. second, third and fourth tube portions and for axially abutting an axial end section of said fourth tube portion during said axial movement of said floating block means toward said main block means and said folding of said third and fourth portions.

2. The invention of claim 1 wherein said main block means include first and second block elements separable along a plane parallel to the axis of said tube and wherein each of said first and second block elements has an axially extending recess which recesses form a bore for clamping said first tube portion upon engage ment of said first and second block elements within said parallel plane.

3. The invention of claim 2 wherein said floating block means include first and second floating elements separable along said parallel plane and each said floating element including a portion of each of said first and second counterbore means.

4. The invention of claim 1 further including biasing means disposed between said main block means and said floating block means for urging said floating block means axially away from said main block means.

5. The invention of claim 2 wherein fluid operated actuator means are provided for selectively moving said first block element away from said second block element in a direction normal to said parallel plane.

6. The invention of claim 1 wherein said second tube portion is disposed along the length of said tube between said third portion and said fourth portion.

7. The invention of claim 6 wherein said punch means includes a reduced section axially extending portion for passage into the interior of said tube and includes an enlarged shoulder portion for abutting engagement with said axial end section.

8. The invention of claim 4 wherein said main block means further include adjustable stop means for limiting the axial movement of said floating block means away from said main block means under the influence of said biasing means.

9. The invention of claim 8 wherein said adjustable stop means include at least one bolt being screw threaded into said main block means and being slide ably disposed within said floating block means.

10. A method of forming a pair of axially spaced radially extending ribs in a tube by folding portions of said tube including the sequential steps of:

a. concurrently fixedly clamping first and second axially spaced portions of said tube in first and second separate clamping means; y

b. non-forceably inserting an elongated punch means into the interior of said tube from one end thereof;

c. moving said elongated punch means axially toward said second separate clamping means in abutting relationship with one end of said tube;

d. moving said second separate clamping means axially toward said first separate clamping means; and

e. radially restraining third and fourth portions of said tube during step (d) wherein said third tube portion is disposed along said tube between said first and second portions and wherein said fourth portion is disposed along said tube between said second portion and said one end of said tube,

thereby folding said portions of said tube. 

1. Apparatus for forming a tube comprising; main block means for holding a first portion of said tube to be formed, floating block means for holding a second portion of said tube to be formed, said floating block means being movable relative to said main block means in a direction coincident with the axis with said tube, said floating block means including spaced-apart first and second counterbore means for receiving third and fourth portions of said tube and forming said third and fourth portions into radially extending ribs on said tube by folding said third and fourth portions upon axial movement of said floating block means toward said main block means, punch means for non-forceable passage into the interior of said first, second, third and fourth tube portions and for axially abutting an axial end section of said fourth tube portion during said axial movement of said floating block means toward said main block means and said folding of said third and fourth portions.
 2. The invention of claim 1 wherein said main block means include first and second block elements separable along a plane parallel to the axis of said tube and wherein each of said first and second block elements has an axially extending recess which recesses form a bore for clamping said first tube portion upon engagement of said first and second block elements within said parallel plane.
 3. The invention of claim 2 wherein said floating block means include first and second floating elements separable along said parallel plane and each said floating element including a portion of each of said first and second counterbore means.
 4. The invention of claim 1 further including biasing means disposed between sAid main block means and said floating block means for urging said floating block means axially away from said main block means.
 5. The invention of claim 2 wherein fluid operated actuator means are provided for selectively moving said first block element away from said second block element in a direction normal to said parallel plane.
 6. The invention of claim 1 wherein said second tube portion is disposed along the length of said tube between said third portion and said fourth portion.
 7. The invention of claim 6 wherein said punch means includes a reduced section axially extending portion for passage into the interior of said tube and includes an enlarged shoulder portion for abutting engagement with said axial end section.
 8. The invention of claim 4 wherein said main block means further include adjustable stop means for limiting the axial movement of said floating block means away from said main block means under the influence of said biasing means.
 9. The invention of claim 8 wherein said adjustable stop means include at least one bolt being screw threaded into said main block means and being slideably disposed within said floating block means.
 10. A method of forming a pair of axially spaced radially extending ribs in a tube by folding portions of said tube including the sequential steps of: a. concurrently fixedly clamping first and second axially spaced portions of said tube in first and second separate clamping means; b. non-forceably inserting an elongated punch means into the interior of said tube from one end thereof; c. moving said elongated punch means axially toward said second separate clamping means in abutting relationship with one end of said tube; d. moving said second separate clamping means axially toward said first separate clamping means; and e. radially restraining third and fourth portions of said tube during step (d) wherein said third tube portion is disposed along said tube between said first and second portions and wherein said fourth portion is disposed along said tube between said second portion and said one end of said tube, thereby folding said portions of said tube. 